Evolution of the near-core rotation frequency of 2497 intermediate-mass stars from their dominant gravito-inertial mode

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Abstract
Context. The sparsely sampled time-series photometry from Gaia Data Release 3 (DR3) led to the discovery of more than 100 000 main-sequence non-radial pulsators. The majority of these were further scrutinised by uninterrupted high-cadence space photometry assembled by the Transiting Exoplanet Survey Satellite (TESS). Aims. We combined Gaia DR3 and TESS photometric light curves to estimate the internal physical properties of 2497 gravity-mode pulsators. We performed asteroseismic analyses with two major aims: (1) to measure the near-core rotation frequency and its evolution during the main sequence and (2) to estimate the mass, radius, evolutionary stage, and convective core mass from stellar modelling. Methods. We relied on asteroseismic properties of Kepler γ Doradus and slowly pulsating B stars to derive the cyclic near-core rotation frequency, frot, of the Gaia-discovered pulsators from their dominant prograde dipole gravito-inertial pulsation mode. Further, we investigated the impact of adding frot as an extra asteroseismic observable apart from the luminosity and effective temperature on the outcome of grid-based modelling from rotating stellar models. Results. We offer a recipe based on linear regression to deduce frot from the dominant gravito-inertial mode frequency. It is applicable to prograde dipole modes with an amplitude above 4 mmag and occurring in the sub-inertial regime. By applying it to 2497 pulsators with such a mode, we have increased the sample of intermediate-mass dwarfs with such an asteroseismic observable by a factor of four. We used the estimate of frot to deduce spin parameters between two and six, while the sample’s near-core rotation rates range from 0.7% to 25% of the critical Keplerian rate. We used frot, along with the Gaia effective temperature and luminosity to deduce the (convective core) mass, radius, and evolutionary stage from grid modelling based on rotating stellar models. We derived a decline of frot with a factor of two during the main-sequence evolution for this population of field stars, which covers a mass range from 1.3 M⊙ to 7 M⊙. We found observational evidence for an increase in the radial order of excited gravity modes as the stars evolve. For 969 pulsators, we derived an upper limit of the radial differential rotation between the convective core boundary and the surface from Gaia’s vbroad measurement and found values up to 5.4. Conclusions. Our recipe to deduce the near-core rotation frequency from the dominant prograde dipole gravito-inertial mode detected in the independent Gaia and TESS light curves is easy to use, facilitates applications to large samples of pulsators, and allows to map their angular momentum and evolutionary stage in the Milky Way.
Funding Information
  • European Research Council (101071505)
  • ANR (ANR-21-CE31-0018-02)
  • Onderzoeksraad, KU Leuven (C16/18/005: PARADISE)

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